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Law enforcement agencies across the UK effectively campaigned to deploy a facial recognition system acknowledged as biased against females, young people, and members of ethnic minority groups, after complaining that a more accurate version generated fewer investigative leads.

The Technology in Practice

British police use the national police database to carry out searches using historical face recognition. This procedure entails comparing a reference photograph of a suspect against a database of over 19 million mugshots to identify possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the system was biased. This acknowledgment came after a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at much greater frequency than Caucasian males. The Home Office stated it “took steps on the findings”.

“It prompts the question of whether facial recognition only becomes effective if users accept discrimination in ethnicity and sex. Operational ease is a poor argument for overriding basic freedoms.”

Long-Standing Problem

Internal documents reveal that this bias has been recognized for over twelve months. Furthermore, police forces argued to overturn an earlier ruling that was intended to mitigate the problem.

Police bosses were notified of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was more likely to suggest false positives for images depicting women, individuals of Black ethnicity, and those aged 40 and under.

A Reversed Decision

In reaction, the National Police Chiefs’ Council (NPCC) ordered that the confidence threshold required for potential matches be increased to a point where the disparity was significantly reduced.

However, this directive was reversed the following month following complaints from police that the modified technology was producing fewer “investigative leads”. Internal records indicate the stricter setting reduced the proportion of searches resulting in possible identifications from 56% to a mere 14%.

Profound Inequalities

Although the authorities refused to say what threshold is now in operation, the recent independent review found the system could produce incorrect matches for women of Black heritage nearly a hundred times more often than for white women at specific configurations.

The Home Office stated on these findings: “Our evaluation identified that in a limited set of circumstances the software is has a greater tendency to wrongly flag some demographic groups in its match reports.”

Operational Effectiveness vs. Bias

Describing the impact of the temporary raise to the system's confidence threshold, the NPCC documents state: “The change greatly lessens the impact of bias across protected characteristics of race, age and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that forces complained that “a previously useful tool now delivered outcomes of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a ten-week consultation on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the independent scrutiny and oversight board for the national policing equality strategy, commented: “There was scant consideration in race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“These revelations show once again that the pledges to combat discrimination the police has undertaken via the equality initiative are not being translated into broader operations. Independent assessments have cautioned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“Any use of facial recognition must meet strict national standards, be subject to external review, and prove it reduces rather than exacerbates racial disparity.”

Home Office Response

A government representative said: “The Home Office takes the findings of the study with utmost gravity and we have already taken action. A updated software has been externally evaluated and procured, which has demonstrated no measurable discrimination. It will be tested early next year and will be subject to further assessment.

“The foremost aim is protecting the public. This gamechanging technology will assist officers to put criminals and rapists behind bars. There is officer review in every step of the procedure and no arrest or charge would be taken without specialist personnel carefully reviewing the output.”